Heat exchangers are used in a wide range of applications for removing heat from or adding heat to a fluid. Typically alternating flows of hot and cold fluid flow through passageways separated by respective thermally conductive plates, the respective hot and cold fluid flows being connected to respective hot and cold fluid plenums through which the hot and cold fluid flows are conducted to and removed from the heat exchanger. Fins may be arranged within the passageways to improve heat transfer from the fluids to the plates and vice versa.
Typically, the heat exchanger comprises a rectangular section shell in which the heat conductive plates are mounted. In certain high pressure and/or high temperature applications, this may lead to pressure and/or thermal fatigue in the shell, particularly in corner regions thereof, which may be undesirable, requiring repair or replacement of the heat exchanger.